1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29#include <sys/stropts.h>
30#include <sys/isa_defs.h>
31#include <sys/nvpair.h>
32#include <sys/sysmacros.h>
33#if defined(_KERNEL) && !defined(_BOOT)
34#include <sys/varargs.h>
35#else
36#include <stdarg.h>
37#include <strings.h>
38#endif
39
40/*
41 * This allocator is very simple.
42 *  - it uses a pre-allocated buffer for memory allocations.
43 *  - it does _not_ free memory in the pre-allocated buffer.
44 *
45 * The reason for the selected implemention is simplicity.
46 * This allocator is designed for the usage in interrupt context when
47 * the caller may not wait for free memory.
48 */
49
50/* pre-allocated buffer for memory allocations */
51typedef struct nvbuf {
52	uintptr_t	nvb_buf;	/* address of pre-allocated buffer */
53	uintptr_t 	nvb_lim;	/* limit address in the buffer */
54	uintptr_t	nvb_cur;	/* current address in the buffer */
55} nvbuf_t;
56
57/*
58 * Initialize the pre-allocated buffer allocator. The caller needs to supply
59 *
60 *   buf	address of pre-allocated buffer
61 *   bufsz	size of pre-allocated buffer
62 *
63 * nv_fixed_init() calculates the remaining members of nvbuf_t.
64 */
65static int
66nv_fixed_init(nv_alloc_t *nva, va_list valist)
67{
68	uintptr_t base = va_arg(valist, uintptr_t);
69	uintptr_t lim = base + va_arg(valist, size_t);
70	nvbuf_t *nvb = (nvbuf_t *)P2ROUNDUP(base, sizeof (uintptr_t));
71
72	if (base == 0 || (uintptr_t)&nvb[1] > lim)
73		return (EINVAL);
74
75	nvb->nvb_buf = (uintptr_t)&nvb[0];
76	nvb->nvb_cur = (uintptr_t)&nvb[1];
77	nvb->nvb_lim = lim;
78	nva->nva_arg = nvb;
79
80	return (0);
81}
82
83static void *
84nv_fixed_alloc(nv_alloc_t *nva, size_t size)
85{
86	nvbuf_t *nvb = nva->nva_arg;
87	uintptr_t new = nvb->nvb_cur;
88
89	if (size == 0 || new + size > nvb->nvb_lim)
90		return (NULL);
91
92	nvb->nvb_cur = P2ROUNDUP(new + size, sizeof (uintptr_t));
93
94	return ((void *)new);
95}
96
97/*ARGSUSED*/
98static void
99nv_fixed_free(nv_alloc_t *nva, void *buf, size_t size)
100{
101	/* don't free memory in the pre-allocated buffer */
102}
103
104static void
105nv_fixed_reset(nv_alloc_t *nva)
106{
107	nvbuf_t *nvb = nva->nva_arg;
108
109	nvb->nvb_cur = (uintptr_t)&nvb[1];
110}
111
112const nv_alloc_ops_t nv_fixed_ops_def = {
113	nv_fixed_init,	/* nv_ao_init() */
114	NULL,		/* nv_ao_fini() */
115	nv_fixed_alloc,	/* nv_ao_alloc() */
116	nv_fixed_free,	/* nv_ao_free() */
117	nv_fixed_reset	/* nv_ao_reset() */
118};
119
120const nv_alloc_ops_t *nv_fixed_ops = &nv_fixed_ops_def;
121